Interesting. I don't think I've heard of it before.

I learnt Esperanto grammar in about 2 weeks about 25 years ago. As my first second language, it helped me to understand English (my native language's) grammar better, and was later a useful bridge to other european languages. While I've forgotten most of my Esperanto vocabulary, I still have a good grasp on the grammar and how to form all the different conjugations.

I think that Interlingua sounds nicer, even though it's a bit more complicated. I never learnt it properly, though.

I think Toki Pona has tremendous potential as an international auxiliary language (IAL), being as simple as it is. But its creator and its community embrace it as an artlang, and seem to collectively disapprove of the idea of making it an IAL.

Which is silly. Esperanto is as it is (moderate amount of vocabulary, but with very simplified grammar) to make it as easy as possible to learn, to encourage its adoption as a lingua franca for speakers of all languages.

Toki Pona beats it hands down in that regard. You can have the entire lexicon and the basic grammar down in a few hours. You can be practiced to fluency within a few days to a couple of weeks.

In some ways, it's too simplistic... but a small official expansion (as few as maybe 50 words) would take care of those issues.

Alas, there's no momentum to do that to the language and sell it as an IAL at this time.

But if it keeps gaining popularity, maybe it can make that jump in the future.

Toki Pona is an interesting conlang for me, less due to its potential role as auxiliary language and more due to how much it highlights that linguistic communication is intrinsically complex - and trying to reduce the complexity in one system will inevitably lead to an increase of complexity elsewhere.

And in Toki Pona's case this means that you aren't memorising just the 123 words, but also a bunch of fixed expressions to refer to things without a word of its own. Such as:

• "toki pona" good language - the name of the language. No, we aren't talking about your favourite language, unless it happens to be Toki Pona.
• "telo nasa" beverage intoxicating - alcohol as a substance, or booze in general.
• "sike tenpo" round time - year. "round" contextually referring to the Earth around the Sun, not e.g. the Moon around the Earth. etc.

You can disambiguate those, sure. Language (as a human faculty) offers you resources for that. But you're going to decrease the information ratio, or you'll need to rely far more on the context, potentially not available for the hearer/reader. And once you take things like this into account, the net result isn't meaningfully more or less complex than a natural language, it's roughly on the same level.

I'll try to learn this. I like the simple principle of limiting words used.